1. Technical Field
The present invention relates to water-pressure controls used in fire-extinguishing piping, and more particularly to a valve control device for fire-extinguishing piping.
2. Description of Related Art
It is well known that fire-extinguishing piping is required by fire services acts in many countries to be provided in all buildings and communal facilities such as bridges and tunnels. Typically, fire-extinguishing piping comprises a water pump and plural sprinkler heads that are connected by pipelines. The water pump pressurizes water so as to deliver fire-extinguishing water to the sprinkler heads for sprinkling water and extinguishing fire. In addition, a deluge valve is installed on the pipeline between the water pump and the sprinkler heads to control the fire-extinguishing water pressurized by the water pump with a preset pressure and control the pressure for opening the valve and supply water, thereby delivering the fire-extinguishing water to the plural sprinkler heads for their synchronous sprinkling water and extinguishing fire.
However, when the fire-extinguishing piping is installed in a tunnel, the distance between the deluge valve and the endmost sprinkler head increases with the length of the tunnel and tends to be too large to remain enough water pressure at the sprinkler heads near the terminal of the fire-extinguishing piping. As a result, the fire-extinguishing capacity at the terminal of the fire-extinguishing piping is degraded.
It is also known that the fire-extinguishing water in fire-extinguishing piping flows to sprinkler heads through the deluge valve. In such a deluge valve, there is a valve port configured to control water flow. The valve port can be open or closed by operating a valve plug that is driven by water pressure. Since the deluge valve contains therein a water-pressure control chamber, and the deluge valve has the valve plug between its water inlet passage and water outlet passage, while the water inlet passage and the water outlet passage are connected to the water-pressure control chamber through respective manifolds, it is possible to use the water pressure within the water-pressure control chamber to drive the valve plug to open and close the valve. Therefore, when the pressure accumulated in water-pressure control chamber makes the fire-extinguishing water flow to the water outlet passage through the manifold, fluid hammer tends to happen in the manifold. This can cause annoying noise, and in some case may damage the manifold over time.
Generally, a deluge valve installed on the fire-extinguishing piping has its water inlet passage or water outlet passage equipped with a switch valve for opening and closing the fire-extinguishing piping. This switch valve generally comprises a manual valve and a solenoid valve. The solenoid valve can only work to open the valve when electrified and activated by a flame sensor. When a fire breaks out in a tunnel, a power failure is likely to come as a consequence. Once this power failure happens, the solenoid valve is closed and the water supply from the fire-extinguishing piping is stopped. The water outage in turn makes the sprinkler heads useless.
Additionally, when flame sensors in a tunnel detect flame or smoke, they activate fire-extinguishing piping to sprinkle at the connected sprinkler heads. Since the sprinkling operation usually starts without providing warning, road users and drivers in the tunnel may be startled, or in some other cases, water may hit people and cars in the tunnel and cause accidents.
These shortcomings relates to the prior art need to be addressed.